JP3587172B2 - Loss equalization method and loss equalizer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a loss equalization method for compensating for variations in the distribution of transmission loss between input and output ports of an optical element for optical communication, particularly an optical element of multiple input and multiple output represented by an AWG or an optical matrix switch. The present invention relates to a loss equalizer.
[0002]
[Prior art]
Currently, in order to construct a high-performance, large-capacity communication system, a technique for realizing switching and interconnection using optical technology has been introduced. Multi-input devices such as a matrix type optical switch and an input / output multi-output type arrayed waveguide type diffraction grating (AWG) filter are used as optical functional devices that realize the above optical switching and optical interconnection and support a large-capacity wavelength division multiplexing network. / Optical elements with multiple output ports are used. As a configuration of such a large-capacity optical communication system, for example, an interconnection configuration utilizing a barrel shifter characteristic of an arrayed waveguide diffraction grating (AWG) for wavelength-multiplexed light is disclosed in No. 308748.
[0003]
By the way, the AWG uses a plurality of optical waveguides having optical path differences to multiplex and demultiplex wavelengths by the interference of light. However, due to the structure of the AWG and the waveguide characteristics of light, the AWG has a combination of connection between input and output ports. And loss distribution characteristics. FIG. 8 is a loss distribution characteristic diagram depending on the combination of the connection between the input and output ports of the AWG.
[0004]
Next, an optical matrix switch will be described as an example of another optical element having multiple input / multiple output ports. Similarly to the AWG, the transmission loss of the connection between the ports of the optical matrix switch has a distribution. For example, in the optical matrix switch having the configuration shown in FIG. 11, there is a loss distribution due to an optical path difference depending on the connected path, and the value is small in the shortest path 42 and large in the longest path 43. FIG. 11A shows a configuration in which the signal light group 10 enters from one direction and is output as the signal light group 11, and FIG. 11B shows that the signal light group 10 and the signal light group 10a are viewed from two directions. A configuration is shown in which signals are input and output as signal light groups 11 and 11a as output signal lights, respectively.
[0005]
Further, as a more specific example, in XVII WORLD TELECOMMUNICATIONS CONGRESS (WTC / ISS2000), J.I. E. FIG. There is a waveguide type optical switch described in "AN ALL-OPTICAL CROSS-CONNECT SWITCH BASED ON TOTAL INTERNAL REFLECTION" published by Fouquet et al. This optical switch has the same configuration as that of FIG. 11, and it is shown that the loss of the switch is substantially proportional to the waveguide loss of the waveguide and the number of passing cross points.
[0006]
For this reason, in order to keep the light intensity of the selected output light constant, it is necessary to perform equalization control of the loss distribution of an optical element having a multi-input / multi-output port such as an AWG. Various optical signal loss equalization methods have been employed.
[0007]
Hereinafter, the related art will be described with reference to the drawings. FIG. 9 is an explanatory diagram for explaining a conventional technique. In FIG. 9, the signal light wavelength-multiplexed and transmitted by the transmitting node 103 is input to the input port of the AWG 101, output to the set output port, and transmitted to the receiving node 104. When passing through the AWG 101, the input signal light 110 suffers a loss depending on the combination of connections between the input and output ports of the AWG 101.
Therefore, in the optical receiver (PD) 141 of the receiving node 104, in order to stably receive the optical signal and perform reliable communication, the intensity of the optical signal incident on the optical receiver 141 is set to be equal to all wavelengths. Needs to be controlled so as to take a constant value.
In order to realize such loss equalization control, in the prior art, a method of observing light intensity for each wavelength at the receiving node 104 and performing feedback control to the transmitting node 103 has been adopted. . Specifically, the incident light of the optical receiver 141 shown in FIG. 9 is monitored by an optical intensity monitor 143 via an optical branch, and the corresponding transmission laser 130 is controlled so that the intensity becomes constant. Output control.
[0008]
Further, as a technique for compensating for the gain wavelength dependence of a specific output, there is an invention described in Japanese Patent Application Laid-Open No. 9-289349 "optical equalizer and optical amplifier and wavelength multiplexing optical transmission apparatus using the same". In the above publication, a plurality of etalon filter plates having different free spectrum regions (FSR) are cascaded to compensate for gain wavelength dependence of an optical fiber amplifier or the like and realize an optical equalizer having low loss polarization dependence. An arrangement is disclosed. However, the invention described in Japanese Patent Application Laid-Open No. 9-289349 does not disclose anything about equalizing the loss distribution of an element having multiple input / multiple output ports.
[0009]
[Problems to be solved by the invention]
The above-described loss equalization method in the related art has the following problems.
[0010]
A first problem is that a system using the wavelength intensity monitor 143 and the feedback signal 140 causes an increase in necessary components, and it is impossible to reduce the cost of the apparatus. For example, a wavelength intensity monitor 143 and an optical branching element 142 for guiding signal light to the wavelength intensity monitor 143 are required. Further, a configuration is required in which a feedback signal 140 for controlling the wavelength intensity from the wavelength intensity monitor 143 to the transmitting node 103 is fed back. In particular, when the distance between the AWG 101 and the transmission node 103 is not short, there is a possibility that the cost of providing a configuration required for transmitting the feedback signal 140 may increase.
[0011]
The second problem is that in a configuration in which the system is extended using multiple optical elements and the input signal light is split, the intensity change of the light source performed for one optical element affects other systems. And it is not possible to cope with an optical element such as AWG having individual differences in loss characteristics.
[0012]
For example, consider the case where the system of FIG. 9 is extended. FIG. 10 shows a system configuration in which AWGs are connected in a mesh form and expanded, and functions such as multicast and broadcast can be provided in a central switch. In such a configuration, if the transmission lasers 130 and the optical receivers 141 do not correspond one-to-one and there is an individual difference in AWG loss, the conventional feedback control method cannot be used. Can not.
[0013]
A third problem is that loss equalization does not converge and the steps required for adjustment become longer.
In particular, considering a configuration in which the transmission node 103 includes the optical amplifier 132, a change in the intensity of one wavelength of the input light to the optical amplifier 132 due to the nonlinearity of the optical amplification characteristic with respect to the wavelength multiplexed light causes Affects the intensity of all other wavelengths. Therefore, when the intensity of the wavelength output to a specific output port 110 (i) is adjusted in the corresponding transmission laser (LD), the wavelength of the wavelength output to another output port 110 (j ≠ i) is adjusted at the same time. This will affect the strength and require repeated readjustments.
[0014]
All of the above three problems are caused by the fact that the distribution of the loss of the AWG is not locally equalized around the AWG, but is compensated using an external system such as a light source. However, AWGs are currently mainly used as wavelength MUXs and DEMUXs, and are not commonly used as barrel shifters (or wavelength routers). Not done enough.
[0015]
Also, regarding the optical matrix switch, since the signal light of an arbitrary input port is connected to an arbitrary output port by switching the switch, the problem of the equalization control of the loss distribution is to deal with the AWG. It can be regarded as the same as the method.
[0016]
In order to solve the above-described problems, the present invention returns the distribution of transmission loss due to the connection between the input and output paths of the multi-input / multi-output optical element configured in a mesh connection state via the wavelength to the transmission laser (LD). Instead, equalization is locally performed in the vicinity of the multi-input multi-output optical element, thereby shortening the adjustment process required for the loss equalization.
[0017]
[Means for Solving the Problems]
A loss equalization method and a loss equalizer according to the present invention have a plurality of input ports and a plurality of output ports, provide optical attenuating means for each input / output port, and adjust the amount of attenuation by the optical attenuating means. , So that the transmission wavelength losses are all adjusted to be equal.
[0018]
The loss equalization method according to the present invention is a loss equalization method for an optical element having a plurality of input / output ports, wherein the loss equalization method measures a transmission loss of signal light output from the input port to a corresponding output port. A measurement step, an equalization amount calculation step of calculating a correction value for equalizing the loss amount of the measurement value measured in the loss measurement step, and a correction value obtained in the equalization amount calculation step. A loss equalizing step of correcting a loss of signal light for each output port.
[0019]
In the loss measuring step, the measurement is performed for each signal light output from each input port to a corresponding output port.
[0020]
Further, the loss measuring step is characterized in that a transmission loss is measured for the signal light output from a specific input port to all the corresponding output ports.
Particularly, the equalization amount calculating step is characterized in that a correction value is calculated based on a correlation of a connection combination between the input port and the output port.
[0021]
The loss equalizer of the present invention has a plurality of input ports and a plurality of output ports, and provides a corresponding optical attenuator for each input / output port, adjusts the amount of attenuation by the optical attenuator, and adjusts the transmission wavelength. Is characterized by equalizing the loss.
[0022]
Further, the loss equalizer includes loss measuring means for measuring a loss from the input port to a corresponding output port, and for each loss value measured by the loss measuring means, an equalization amount for calculating a correction amount. And a calculating means.
[0023]
Further, the present invention supports n × m (n, m is an integer of 1 or more) multi-input multi-output optical element having n input ports and m output ports, and n input ports. loss measuring means for measuring a loss to the m output ports, and an attenuation calculating means for calculating an attenuation value of the input signal light with respect to the n × m loss values measured by the loss measuring means. .
[0024]
Further, the present invention provides an n × m (n, m is an integer of 1 or more) multi-input multi-output optical element having n input ports and m output ports, and m input ports corresponding to a certain input port. , And m + n-1 loss measuring means of n-1 losses in the opposite direction excluding the direction symmetrical to the output port, each of which is measured by the n + m-1 loss measuring means. And an attenuation calculating means for calculating an attenuation value of the input signal light for the loss value.
Further, the loss equalizer further includes an optical attenuator for adjusting the amount of attenuation for each input / output port based on the amount of attenuation calculated by the amount of attenuation calculator.
[0025]
As described above, according to the present invention, the distribution of the transmission loss due to the connection between the input and output paths of the multi-input multi-output optical element such as the AWG or the optical matrix switch configured in the mesh connection state via the wavelength is transmitted to the transmission node. Since the localization is performed locally near the multi-input multi-output optical element without feedback, the adjustment process required for the loss equalization can be shortened, and the equalization control is performed by connecting the input light to a plurality of AWGs. Is also possible.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention particularly relates to a loss equalization method and a loss equalization apparatus for a plurality of optical elements, and the loss equalization apparatus referred to herein is an optical element, a circuit, or a configuration including the function of the present invention. It is possible to implement including the apparatus configuration performed. FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
[0027]
In the configuration of FIG. 1, in the first embodiment, the AWG element 1 having n input / output ports 10 and 11, input-side optical attenuating means 20 for each of the input and output ports, And a damping means 21. In FIG. 1, a 16-port AWG using a quartz optical waveguide is used as the AWG 1. Also, a case will be described in which a total of 32 variable optical attenuators using an interference film filter are used as the optical attenuating means 20 and 21, each of which includes 16 variable optical attenuators.
[0028]
FIG. 7 is an explanatory diagram showing a connection example of AWG wavelengths each having 16 ports for input and output. FIG. 12 is an example of wavelengths at intervals of 100 GHz according to the ITU-T standard as an example of wavelengths λ1 to λ16 used in 16 ports, and an actual measurement value and a simulation value described in the following description correspond to λ1 of this wavelength band. Λ16 value.
[0029]
A measurement example of transmission loss between all input / output ports in an AWG element as shown in FIG. 7 will be described. Each signal light input to the input ports i1 to i16 in the AWG having the configuration of FIG. 7 can be output to the output ports o1 to o16. FIG. 13 illustrates an example of the input / output relationship between the input / output ports of the 16-port AWG and the wavelength. For example, the signal light of the wavelength λ1 input to the input port i1 is output to the output port o1, This indicates that the signal light of λ16 input to the input port i1 is output to the output port o2. In addition, there are 256 points of 16 ports × 16 ports for each wavelength to be measured. FIG. 14 shows the loss due to the path length of the signal light passing through each port. As shown in FIG. 14, the difference between the loss at the maximum path (optical path) length and the minimum loss is 4.53 dB.
[0030]
In the first embodiment of the present invention, the attenuation of the variable optical attenuators 20 and 21 as shown in FIG. Is adjusted so that the transmission wavelength loss is equal for each input / output port. Specifically, the attenuation of the variable optical attenuator connected to the central port having a short path length is increased, and the attenuation is reduced toward the periphery. The optimum value of the entire balance of each loss amount is calculated using a calculation method such as the least square method. In the configuration shown in the figure, the loss of all 256 paths can be measured, and the optimum value of the adjustment value at 32 points can be obtained. A method of solving analytically, an approximation that minimizes the sum of the first power of the difference, and a method of numerically obtaining an optimum value using a computer can be adopted. That is, the present invention focuses on the correlation of the optical signal by the combination of the connection of the input port and the output port with respect to the optical element having a plurality of input / output ports, and is not limited to the above calculation method. An optimal calculation method is applied according to the configuration and characteristics.
[0031]
By appropriately setting the attenuation of the input / output optical attenuating means 20 and 21 based on the optimum value obtained in this way, the loss distribution of the AWG element 1 depending on the path length due to the combination of the connection between the input and output ports is equalized. It becomes possible.
[0032]
As described above, since the light intensity attenuating means is provided to both of the input and output ports of the AWG and the loss is locally equalized around the AWG, the feedback control can be eliminated. It is also possible to perform equalization control in a connection where input light is branched into a plurality of AWGs.
[0033]
Further, by integrating the light attenuating means 20 and 21 and the AWG 1, it is possible to adjust in advance in the manufacturing stage, and to sell and purchase an AWG having a uniform loss characteristic. Complex light intensity adjustment can be eliminated.
[0034]
Although the first embodiment of the present invention has been described above, in the above-described embodiment, the AWG 1 is a semiconductor waveguide formed on an InP substrate or an AWG using an optical waveguide formed on an organic substrate. Can be used.
[0035]
Further, as the optical attenuating means 20, 21, a variable or fixed waveguide type optical attenuator, a fixed optical attenuator connected outside the AWG, an interference film filter, or the like, which is collectively created on a waveguide substrate for creating an AWG, is used. A variable or fixed optical attenuator built in a portion where the element and the fiber are bonded and fixed, or a fiber type attenuator whose loss amount can be varied by means such as heat or ultraviolet irradiation can be used. Further, as the optical attenuators 20 and 21, similarly to the optical attenuator, a semiconductor modulator using an electric field optical effect, a semiconductor optical amplifier, or a fiber amplifier using a rare earth represented by Er or the like can be used.
[0036]
Since the attenuation of these modulators and the gain of the amplifier can be electrically adjusted externally, the loss distribution of the AWG 1 can be made uniform by changing the amplification factor as in the case of the variable attenuator. Further, the connection between the AWG element and the modulator or the amplifier is connected to the outside of the AWG via a fiber, or a part or the whole is integrated on a substrate forming the AWG, or a hybrid mounting technique is used. Integrated structures are also possible. Further, a configuration may be adopted in which the above-described optical attenuator, modulator and optical amplifier are combined and applied to the input and output optical attenuating means 20 and 21. As described above, the variable attenuating means is provided for each input / output port, the attenuation of the variable optical attenuator is adjusted, and the losses of the transmission wavelengths are adjusted to be equal, and the overall balance of each loss is minimized. An optimal value is obtained using a calculation method such as a square method. In addition, in order to measure the loss of all 256 paths and find the optimum value of the adjustment value at 32 locations, there is also a method of analytically solving a simultaneous equation of 32 elements or finding the optimum value numerically using a computer. Can be adopted.
[0037]
Further, in the above embodiment, the value of the amount of attenuation is provided in advance from the manufacturer without attaching the optical attenuator, and the user is required to provide the amount of loss of the optical attenuator connected to the outside of the AWG or the amplifier. Means for setting the amplification factor can also be adopted.
[0038]
As described above, the first embodiment of the present invention has been described. As an application, a configuration using a matrix type optical switch instead of an AWG as a multi-input multi-output optical element will be described. FIG. 2 is a configuration example of a loss equalizer of the present invention using a matrix type optical switch. In FIG. 2, each signal light input from the incoming line passes through the passing cross point 7, is reflected at the set reflection cross point 8, and is output to the outgoing line.
Also in the configuration using the matrix type optical switch, variable attenuation means is provided for each input / output port, the attenuation of the variable optical attenuator is adjusted, and the loss of the transmission wavelength is adjusted to be equal. The optimum value of the total balance of the quantities can be determined by using a calculation method such as the least square method.
[0039]
Such an optical switch for appropriately setting the amount of attenuation of the input / output light attenuating means 20, 21 uses LN, quartz, an optical semiconductor or an organic material, and utilizes a thermo-optic effect, an electro-optic effect, or a refractive index matching. As the internal connection circuit, a waveguide type optical switch equivalent to that shown in FIG. 11 is applicable. For example, a switch based on Si-MEMS (Micro-Electronic-Mechanical System) or a liquid-refractive-index adjusting material as described above is used. The internal connection circuit used as the above is a circuit equivalent to FIG. 11, and a waveguide type optical switch using quartz or an organic material is applicable.
[0040]
Next, a second embodiment of the present invention will be described. In the first embodiment, the measurement of the connection loss of all the wavelength-ports of the AWG has been described. However, taking a 16-port AWG as an example, the number of measurements increases to 256 connections, which is a huge measurement. It requires time and effort.
[0041]
Therefore, based on the configuration of the AWG for equalizing the loss distribution described in the first embodiment, FIG. 3 is used to solve such a problem relating to the measurement time and adjustment for each port. A second embodiment will be described.
[0042]
In this embodiment, in order to simplify the measurement of the loss characteristic, the value of the attenuation amount of the optical attenuating means is determined by measuring only the loss of all the ports facing each other from any one port of the input and output. Adopt the technique.
[0043]
In other words, focusing on the man-hours required in the manufacturing stage of the AWG in which the two groups of variable optical attenuating means 20 and 21 on the input side and the output side described in the first embodiment are integrated, for example, In the case of an AWG having 16 ports each, the number of mesh connections is 256 connections, so that the transmission loss has 256 values each. Strictly speaking, the loss of these 256 connections is measured. After that, it is necessary to determine the optimum value of the attenuation amount of the two groups of light attenuation means.
[0044]
On the other hand, when attention is paid to the arrangement of the input / output ports of the AWG on the element and the amount of loss, the loss generally has a characteristic that the center of the ports arranged in parallel is small, and the loss increases monotonically toward both ends. You can see that.
[0045]
Therefore, if only the loss of all the ports facing each other from the arbitrary one port of the input and output is measured, in the case of the 16-port AWG, there are 31 kinds of measurements.
[0046]
By using the 31 kinds of loss values and the least squares method using a computer, the values of the attenuation amounts of the two groups of light attenuating means are calculated without measuring the 256 kinds of loss characteristics that form an AWG mesh. Is the thing. Hereinafter, the procedure of the second embodiment will be described with reference to the drawings. FIG. 3 is an explanatory diagram illustrating a simplified measurement method according to the second embodiment.
[0047]
In FIG. 3 (a), the transmission loss from any one port from the input side to all the output side ports is measured, and in FIG. 3 (b), the transmission loss from any one port from the output side to all the input side ports is measured. This shows that the transmission loss is measured. Here, since the transmission characteristics of the AWG have no directionality, the measurement in FIG. 3B can be performed without any problem.
[0048]
When the 31 measurement results shown in FIG. 3 are redrawn on the loss distribution characteristic diagram depending on the combination path of the input / output port connection in FIG. 8, the measurement points correspond to the measurement points shown by the thick lines in FIG. . As shown in FIG. 8, the loss distribution characteristic has a clear correlation with the combination of the connection ports, and the change in the loss value from any port with respect to the measured value in FIG. Thus, the relative difference between the loss values can be regarded as substantially constant. If the adjustment is made so as to equalize the loss at the representative 31 measurement points plotted in FIG. 4, the loss equalization with constant accuracy is performed for all the ports.
[0049]
FIGS. 5A to 5C illustrate a process of correcting the loss of all 256 connections using only the numerical values of the 31 points. FIG. 5A shows measured values of the loss before correction.
[0050]
Next, the attenuation of the attenuator 20 on the input side is adjusted using the measured values corresponding to the measurement points in FIG. 3B so that the losses of the paths connected to the output port number 7 are all equal. I do. FIG. 5B shows the result of reflecting the amount of attenuation in FIG. 5A.
[0051]
Next, the attenuation of the output-side attenuator 21 is adjusted so that the loss of the signal light connected to a certain port, for example, the input port number 7 corresponding to the measured value in FIG. I do. FIG. 5C shows the result of reflecting the amount of attenuation in FIG. 5B. In such a process, as shown in FIG. 5C, by using the measured value of a part of the loss, it is possible to flatten the loss of all the connections.
[0052]
Further, the loss measurement has uncertainties due to errors and manufacturing variations. Regarding the value corresponding to the measurement in FIG. 3 (a or b), an average value of a large number of samples is used, or theoretically An optimal value can be obtained by fitting using the least squares method based on the obtained function. The function that can be theoretically obtained is a function that can be obtained by theoretically analyzing the light propagation characteristics of the array waveguide and the slab waveguide of the AWG. FIG. 6 shows the result of optimizing the value of the vessel.
[0053]
FIG. 6 is an example of actual measured values of the loss of a path uniformized using the concept of the loss equalization of the present invention. The result is obtained by using the gain of the optical amplifier instead of the attenuator. .
[0054]
According to FIG. 6, it can be seen that the variation width of all the ports is made uniform from the initial 4.53 dB to only 0.5 dB or less. FIG. 15 shows the gain of the optical amplifier at this time.
Thus, good characteristics were obtained using the set values for each port.
[0055]
Also, in the second embodiment, as in the first embodiment, a similar method can be applied to an optical switch having the configuration shown in FIG. 2 instead of the AWG. That is, in the optical matrix switch, similarly to the AWG, the value of the amount of attenuation of the optical attenuating means is determined by measuring only the loss of all ports facing each other from any one port of input and output. Is possible. Further, the constituent means of the invention can replace the same device as that of the first embodiment.
[0056]
【The invention's effect】
As described above, according to the present invention, the connection between the input and output paths of an optical element having multiple input / multiple output ports, such as an AWG or an optical matrix switch, configured in a mesh connection state via a wavelength as described above. The distribution of the transmission loss due to the above is locally equalized near the AWG or the like without returning to the LD, the adjustment process required for the loss equalization is shortened, and the input light is further reduced as shown in FIG. Can be controlled in a connection branched to a plurality of AWGs.
[0057]
In addition, by integrating the light attenuating means with the AWG or the like, it is possible to adjust the temperature in advance at the manufacturing stage, and to sell and purchase an AWG having a uniform loss characteristic. Adjustment of strength can be eliminated.
[0058]
Further, in the present invention, in order to simplify the measurement of the loss characteristic, the value of the attenuation amount of the optical attenuating means is determined by measuring only the loss of all the ports facing each other from any one port of the input and output. Since the method is employed, it is possible to provide a highly accurate loss equalizer with a simple configuration.
[0059]
A first effect of the present invention is that, for an AWG or an optical switch having a distribution of transmission loss, local correction is performed around the optical device without using complicated and slow-convergence feedback control, so that it is easy and It is possible to obtain stable characteristics.
[0060]
The second effect of the present invention is that, in order to equalize the loss variation of the optical element having the mesh connection between the input and output of multiple ports, the measurement of the loss between all the input and output, which has been conventionally performed, is greatly reduced. It is possible to do. As an example, in the case of an AWG with 16 ports, the measurement amount is reduced to 1/8 because the measurement of 31 paths can sufficiently be performed with respect to 256 paths.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a loss equalization apparatus according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a loss equalizer of the present invention using a matrix switch.
FIG. 3 is a schematic diagram showing a simplified measurement for loss uniformization.
FIG. 4 is an image showing actual measurements using simplified measurements.
FIG. 5 is an explanatory diagram showing a simplified procedure of uniformization.
FIG. 6 is an example of a measured value of a loss of a path that is equalized by using the present invention.
FIG. 7 is an explanatory diagram showing an AWG connection.
FIG. 8 is a distribution characteristic diagram of a loss depending on a route of a combination of connection between input and output ports of the AWG.
FIG. 9 is a block diagram for explaining a conventional technique.
FIG. 10 is an expanded block diagram of a conventional optical communication system.
FIG. 11 is a configuration diagram of an optical matrix switch.
FIG. 12 is a chart showing an example of wavelengths at 100 GHz intervals according to the ITU standard.
FIG. 13 is a table showing a relationship between input / output ports of a 16-port AWG and wavelengths.
FIG. 14 is a table showing an example of actual measurement of losses in all connection paths of the AWG.
FIG. 15 is a table showing variable gain values of AWG input / output optimized by using the present invention.
[Explanation of symbols]
1,101 AWG
6 Matrix optical switch
7 crossing points
8 Reflection Crosspoint
10 Input WDM signal light
11 Output WDM signal light
20 Input side optical attenuator
21 Optical attenuator on output side
20, 21 Variable attenuator
40 Measured loss from input port to all output ports
41 Measured loss from output port to all input ports
103 Sending node
104 receiving node
131 Light source laser
132 optical amplifier
141 Optical Receiver
143 Wavelength intensity monitor
142 Optical Branch
140 feedback signal

Claims (13)

A loss equalization method for an optical device having a plurality of input / output ports, wherein the nonlinear loss distribution of the optical device for each path is adjusted by adjusting a correction amount for each input port and each output port. A loss equalization method characterized by equalizing a loss amount based on a loss distribution. The loss distribution of the transmitted light is measured for each combination path of the connection of the input port and the output port, and the loss distribution is so set that the transmitted light is uniformly output regardless of the combination of the connection of the input port and the output port. 2. The loss equalization method according to claim 1, wherein a correction amount at each of said input ports and each of said output ports is calculated based on a loss amount caused by the above. a loss measuring step of measuring the loss of n × m paths from n input ports to m output ports (n and m are integers equal to or greater than 1), and n × m paths measured by the loss measuring step Is calculated based on the loss values of the n input ports and the m output ports such that the transmitted light is uniformly output regardless of the combination of the connection of the input port and the output port. Loss equalization comprising: an equalization amount calculation step; and a loss equalization step of correcting a loss of signal light for each of the input port and the output port based on the correction amount calculated in the equalization amount calculation step. Method. m pieces from one input port of the n input ports (n, m is an integer of 1 or more) and the loss of a path leading to the output port of which a symmetrical m-number of the output of one of the output ports a loss measuring step of measuring a loss of m + n-1 single path except the overlapping direction leading to n input ports from a port, on the basis of the loss value measured by the n + m-1 or loss measuring step, wherein An equalization amount calculating step of calculating a correction amount in the n input ports and the m output ports so that transmitted light is uniformly output regardless of a combination of connections between an input port and the output port; A loss equalization step of correcting a loss of signal light for each of the input port and the output port based on the correction amount calculated in the equalization amount calculation step. The loss equalization step, an optical amplifier, an optical attenuating either the light modulator, or loss equalization method of claims 1 to 4, wherein the performing by the combination. A loss equalizer in an optical element having a plurality of input ports and output ports, wherein the optical element has a non-linear loss distribution characteristic for each combination path of connection of the input port and the output port, A loss equalizing means having a correction value for equalizing a loss amount based on the loss distribution characteristic of each of the input ports and the output ports. A loss equalizer in an optical element having a plurality of input ports and output ports, wherein the optical element has a non-linear loss distribution characteristic for each combination path of the connection of the input port and the output port, Loss equalizing means having, at each of the input port and the output port, a correction amount calculated based on a loss amount due to distribution so that transmitted light is uniformly output irrespective of a combination of connections between the input port and the output port. A loss equalizer, comprising:
8. The loss equalizer according to claim 6, wherein the loss equalizer is applied by using one of an optical attenuator, an optical modulator, and an optical amplifier, or a combination thereof. 9. The apparatus according to claim 8, wherein the loss equalizer sets a loss amount of an optical attenuator connected to the outside of the loss equalizer , a modulation amount of an optical modulator, or an amplification factor of an optical amplifier. Loss equalizer. 10. The loss equalizer according to claim 6 , wherein the loss equalizer is electrically adjustable from the outside. 11. The loss equalizer according to claim 6, wherein the multi-input multi-output optical element is an array guided diffraction grating (AWG). 11. The loss equalizer according to claim 6, wherein the multi-input multi-output optical element is an optical matrix switch. 12. The loss equalizer according to claim 11, wherein the multi-input multi-output optical element is an AWG based on a semiconductor waveguide formed on an InP substrate or an optical waveguide formed on an organic substrate.

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